Known data storage servers and application servers, allow usage by a plurality of users, relying on the server to provide either data storage capacity, or application functionality. Examples of such prior art servers, used by a plurality of users includes network attached storage devices (NAS), providing data storage functionality to a plurality of client computers.
In the case of a server providing data storage capacity, each user may utilize a variable amount of data storage capacity depending upon the users particular needs.
In prior art network attached storage devices, there may be extreme variation in the amount of data capacity which each client computer uses, since different clients may store different amounts of data. Further, since the data can be compressed by varying degrees, this introduces another variability in the data capacities which can be stored by each client computer. Typically, in prior art network attached storage devices, there is no limit to the number of users which can be assigned to a server computer entity. Assignment of users to a server computer entity is made by an administrator via a user console comprising a visual display unit, keyboard, and pointing device such as a mouse or the like.
It is also known that network attached storage devices may be provided in the form of headless computer entities, also known as “headless appliances”. A known headless computer entity comprises a data-processor, memory, a plurality of input/output ports or the like, and an operating system. Headless appliances are generally designed without user interfaces, and lack a keyboard, pointing device e.g. mouse or track ball, and visual display monitor. This has the advantages both of reducing the cost of ownership, since the cost of a user interface hardware need not be borne by the purchaser, and also inhibiting interference with the operation of the appliance.
In a headless computer entity, human administrators are conventionally allowed only very limited access to the computer entity for maintenance, or in some cases no user maintenance is permitted.
Known headless computer entities have fixed data storage disk configurations of a pre-determined data capacity. Customers cannot upgrade the disk configuration and increase the amount of application data held on a headless computer entity, once purchased. This helps to protect against customer mis-configuration of the appliance, and also protects the manufacturers pricing scheme where headless computer entities are sold with price dependent on data storage capacity.
There is a problem with known server computer entities serving functionality to a plurality of users, that the amount of functionality, for example data storage capacity, required for each user is variable with a wide degree of variation, and conventionally, adding or removing new users from a server computer entity requires intervention from a human administrator. Further, there is no embedded limit on the number of users which can be added to a server computer entity. Therefore, there is a possible scenario that too many users can be added to a server computer entity, and the users can increase their utilization of the computer entity's functionality to an extent where the combined demand from the plurality of users exceeds the available functionalities supplied by the computer entity. This problem is present both in conventional computer entities having a administration console, and in headless computer entities. Because of the lack of administration console the problems are more acute in headless computer entities.